Steam generator and furnace therefor



March 31, 1931. J. J, C, BRAND 1,798,830 I STEAM GENERATOR AND FURNACE THEREFOR Filed June 6, 1927 2 Sheets-Sheet 1 1 3 e; j 1 g3 f fr@ w 6 4 I@ g Jl 2 /l fw \d a f c i a r d d l d"\ March 31, 1931. L J. C, BRAND 1,798,830

STEAM GENERATOR AND FURNACE THEREFOR Filed June 6, 1927 2 Sheets--Sheerl 2 Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE JAMES JOHN CANTLEY BRAND, OF STRAND, LONDON, ENGLAND, ASSIGNOR HALF TO iBRYAN LAING, OF LONDON, ENGLAND OF ONE- STEAM GENERATOR AND FURNACE THEREFOR Application led .Tune 6, 1927, Serial No. 196,916, and in Great Britain June V18, 1926i.

This invention relates to steam generators and furnaces, more especially intended for the utilization of powdered solid fuel as, for example, in the manner described in the specification of my prior application Serial Number 190,119, the chief obj ect of the present in` vention being to provide improved methods of burning the powdered fuel in a confined space in which the passages for the heated gases are so arranged as to ensure that the velocity of the gases is substantially constant, thus providing more eflicient and economical combustion than has hitherto been the case. While the invention is more particularly directed to the burning of pulverulent carbonaceous material such as powdered raw black coal, lignite, brown coal, coke and the residue from low temperature distillation or carbonization, or pitch, peat and like materials, the furnace is also adapted for the burning of liquid fuel.

According to one feature of the present invention the combustion space is mainly or entirely surrounded by, generator tubes which extend between the steam and the water drums and through which the combustion,

gases pass in an inwardly or outwardly direction on their way from the combustion space to the chimney, funnel, or stack. The generator tubes may be substantially vertical, and straight or slightly bent and a centrally located feed drum may be provided. According to another feature of the present invention the liquid or powdered fuel may be sprayed from above or from the sides into the combustion space so that in cases where the cornbustion space is centrally located the gases pass outwards through the generator tubes which mainly or entirely surround the said combustion space or, in cases in which the combustion space mainly or entirely surrounds the generator tubes, the gases pass inwards to a central space leading to an exit flue for the spent gases. When the combustion space is centrally located the generator tubes form a cool wall therefor but when the combustion space surrounds the generator tubes, water tubes may be provided and located in the outer wall thereof so as to form a cool wall for the combustion space. The

steam and water drums may be of annular construction or, alternatively, a plurality of separate cylindrical steam and water drums may be provided, the steam drums being located above the water drums and the several steam drums, as also the water drums, being located at an angle to one another. A suitable arrangement according to the last mentioned construction consists of four cylindrical water drums located at right angles toone another and four superimposed steamdrums also lo-' cated at right angles to one another, the steam drums and the water drums beingl cross conr nected for circulation purposes and the steam and water drums being also inter-connected by a large number of straight, inclined or curved generator tubes arranged around a central combustion space which contains in its lower part the feed water drum, the ar-A rangement of the parts being substantially of frustrum pyramidal or truncated pyramidal configuration. According to another feature i of the present invention the superheater is located within a superheater chamber which is fed directly with live gases from the combustion space and the degree of superheat is thus under complete control.l The superheater may have vertical or curved tubes leading from 'the steam drum or its may comprise horizontal tubes lapped around the steam drum and disposed within a special casing.

In order that the said invention may be clearly understood and readily carried into effect the samewill now be described more fully with reference to the accompanying drawings, in which v Figure 1 is a sectional eleva-tion of a con structionof steam generator in which the combustion space is centrally arranged and the burners arranged around the top of the combustion chamber, the steam and water drums being of annular construction and surrounding the combustion space.

Figure 2 is a half sectional elevation, and.

Figure 3 is a half plan, the quarter plan shown at the left-hand side of the figure being a section through the line 3-3 of Figure 2, and the quarter plan on the right-hand side of the figure being a section through the line 3', 3 of` Figure 2, In this construction there are provided around a central combustion space, four cylindrical water drums arranged at right angles to one another and four cylindrical steam drums also arranged at right angles to one another and disposed above the water drums, the steam 'and water drums being connected together by curved generator tubes, the arrangement being either cubical or approximately of frustrum orv truncated pyramidal form.

Throughout the drawings the same reference letters have been employed to indicate the same or equivalent parts.

Referring to Figure l a is an annular steam drum, Z) isY an annular water drum, c is a feed drum, and (Z, `cZ are small diameter generat'or tubes which extend vertically between the water and the steam drums and circumferentially surround; the centrally located combusti-on space. c is the feed water drum which is situated at the bottom o'f the combustion space and connected to the water drum by the feed water tubes (Z2 which form a water screen 'for the ashpit j2. e', e are the burners, six of which may be provided. e3 is the air box which surrounds the burners e. The combustion chamber e has a refractory lining e* "and at its top it is provided withV a manhole e5. f is the Vsuperheat'er casing which surrounds the generator tubes Z and contains the superheater tubes f3 the latter extending from the steam drum a to the annular superhe'ate'r header f". is the outer rsurrounding casing of the generator and v is'the uptake the latter beingof annular configuration and its lower portion being situated between 'the superheater casing and the outer casing 1I of the generator. 7L,-h are dempers for 'admitting hot combustion gases to the sup'erheater casing. f7, f7 are additional dampers for 'the superheater casing. Z is an annular air heater the tubes Z', Z of which are located in the annular Hue (u. Air enters the air heater IZ by the pipes Z2, Z2 and Z3, vZ3 are pipes which conduct the hot air from the air heater Z to the air box e3 of the burners e.

Referring to Figures 2 and 3, a, a are four cylindrical steam drums disposed at right angles to one another; b, vZ) are four cylindrical water drums disposed'beneath the steam drums and also located at right angles to one another. d, Z are the generator tubes which extend between the `steam Ldrums a, a and the water drums b, Z). e is the combustion chamber which is located centrally of the generator and e', e are powdered vfuel burners located in inclined walls e6, e6 disposed between each contiguous pair of superimposed cylindrical steam and water drums. In this embodiment the generator tubes also surround the 'combustion space e 'while the general arrangement of the steam and water` drums with their interconneeting generator. tubes produces steam generator approxi mately of frustrum or truncated pyramidal configuration. It is to be understood, however, that any desired number of steam and water drums may be employed and that they need not necessarily be arranged at right angles to one another, as in the example illustrated. Furthermore, the steam vdrums may be located vertically or otherwise above the water drums i. e., a cubical, rhomboidal, or 'similar arrangement may be adopted. By reason of the 'aforesaid arrangement of steam and water drums, as also the interconnecting generator tubes, the drums can be made of any desired length, so as to accommodate any required number of generator tubes, thus providing a standard design of generator for any required steam raising capacity.

Four powdered fuel burners e, e are provided in the example illustrated but any multiple Vof four may be provided. cis the feed drum which is connected by tubes d2, Z2 to the Water drum Z), the tubes d2, Z2 forming 'a water screen for the ashpit The feed drum c is covered with refractory material c, and in the example illustrated thefu'el burners e', e are adapted to inject the powdered fuel radially of the feed drum 0 so that the gases of combustion whirl around the same. The location of the vfeed water drum c centrally of the combustion space 'and the fact that it is covered with refractory material, is of especial importance when it is proposed to use powdered fuel having a low volatile content, as, in such instances, therefractory material on the feed drum c becomes highly heated and adords a ready means of re-igniting the powdered fuel during intermittent stoppages of the powdered fuel burners. f is a dome shaped casing for the superheater, the latter being disposed vertically above the feed water drum 0. f3, f3 are curved superheater tubes which'follo'w the arc ofthe outer casing f and which extend between the steam drums a, a an'd a super'- heater steam drum f6. Theb'aise -of the superheater steam drum f6 is lined with refractory material f7.' The superheater chamber f is" v separated from the combustion space 'proper by a roof 0 composed of refractory material, the latter being provided with a'number of openings o controlled by valves 0 through which live gases from the vcombustion chamber e can be admitted to the superheater,

chamber f. The spent combustion gases from the superheater chamber f pass to the duct 'u through tubes h2, 7a2. In the example illustrated a 'series of radiant 'tubes eZ', CZ are also provided lwhich also serve as a water screen to t-hey generator tubes proper eZ. Y The tubes -rZ are embedded in refractory material (Z4, d4, which,nbesides rendering the tubes d,

IZ radiant tubes, also serves as a baffle to cause the combustion gases to take `a circuitous' path through thegenerator tubes inpassing from the combustion space e to the "duct fv. o is the outer shell of the steam generator. j', y" are ashdoors and p is a tube for conducting vapour from the feed drum c to the steam drum a. The roof which serves to separate the combustion chamber e from the superheater chamber f is also composed of refractory material and has embedded therein a series of tubes 1', 7 which extend between the steam drums and which cross each other at right angles, the tubes serving as a water screen for the roof 0 and also as auxiliary steam generating tubes.

In this as also the construction previously described any desired number of balles of refractory material similar to Z4 may be provided and suitably arranged relatively to one another so as to convert as many as desired of the generator tubes into radiant tubes.

In the embodiment of the invention shown at Figures 2 and 3 the area for the combustion gases through the generator tubes also decreases in proportion to the decrease in volume due to 'the drop in temperature of the said gases so that the velocity is constant for the mean temperature difference.

What I claim and desire to secure by Letters Patent of the United States is l. A steam generator comprising superimposed steam drums and water drums, gen* erator tubes disposed in a substantially vertical plane in the path of the combustion gases from a combustion chamber and interconnecting said superimposed steam drums and water drums, a feed Water drum located centrally of the base of the combustion chamber, tubes extending outwardly from said centrally located drum to one of said other drums, a superheater chamber, superheater tubes located within said superheater chamber, and means for admitting a controlled volume of gases directly from the combus tion chamber to said superheater chamber.

2. A steam generator comprising superimposed steam and water drums, generator tubes interconnecting said steam and water drums and located around a central space through which combustion gases pass, a feed water drum at the base of said central space, radially arranged tubes interconnecting the feed water drum with the Water drum, an ashpit beneath said radially arranged tubes, said feed water tubes forming a cool wall for the ashpit.

3. A steam generator comprising superimposed steam and water drums, generator tubes interconnecting said steam and water drums and located around a central space through which combustion gases pass, a feed water drum at the base of said central space,

radially arranged tubes interconnecting said feed water drum and said water drum, said feed water tubes forming a cool wall for the ashpit, refractory material covering said feed water drum, and powdered fuel burners adapted to direct the products of combustion' towards said refractory covered feed water drum, said refractory material serving to store up the necessary heat for the re ignition of the powdered fuel after a temporary stoppage of the burners.

4. A steam generator comprising superimposed steam drums and water drums, generator tubes interconnecting said steam drums and water drums and surrounding a central combustion space, a feed water drum disposed in said combustion space, tubes connecting said feed water drum to said water drums, and a plurality of fuel burners disposed externally of said generator tubes and arranged to project the products of combustion through the generator tubes to said central combustion space.

5. A steam generator comprising a plurality of separate cylindrical steam drums and water drums disposed above one another and connected by generator tubes, said generator tubes surrounding a centrally located combustion space, a feed water drum disposed centrally of .the lower part of said combustion space, and tubes connecting said feed water drum with said water drum.

6. A steam generator comprising four cylindrical water drums located at right angles to one another and foursuperimposed steam drums also located at right angles to one another, generator tubes interconnecting said superimposed steam drums and water drums, said generator tubes surrounding a central combustion space, a feed Water drum disposed centrally of the lower part of said combustion space, tubes connecting said feed water drum with said water drums, fuel burners located between the ends of each pair of steam drums and water drums, and arranged to project combustion gases between the generator tubes into the central combustion space.

7. A steam generator comprising a plurality of separate cylindrical steam drums and water drums disposed above one another and connected together by generator tubes, said generator tubes surrounding a centrally located combustion space, a superheater chamber disposed at the top of said combustion space, a superheater header disposed within said superheater chamber, tubes connecting said superheater header with said steam drums, a wall of refractory material separating said superheater chamber from said centrally located combustion space, said wall being provided with openings through which hot combustion gases pass directly from the combustion space to said superheater chamber, a centrally located feed water drum, and tubes connecting said feed water drum to said water drums.

8. A steam generator chamber comprising a plurality of water drums, a plurality of steam drums disposed above said water drums, generator tubes connecting said water drums to said steam drurns, said generatorV tubes surrounding a, 'Central combustion space, a superheater chamber, a Wall sepa,- rating said superheater chamber from said central combustion space, openings in said Wall for alowing hot combustion gases to pass from the said central combustion space to the said superheater chamber, tubes in oontact with said Wall and interconnecting the steam drums, a centrally located feed Water drum, and tubes connecting said feed Water drum to said Water drnmq JAMES JOHN CANTLEY BRAND. 

